A single-phase variable frequency power supply is a power supply system that can convert AC power into high-quality controllable DC power. Its frequency conversion technology can be used to adjust the output voltage and frequency and realize a variety of power control methods.
1. What is a single-phase variable frequency power supply
A single-phase variable frequency power supply refers to a power supply device that converts AC power signals into DC power signals that can adjust the voltage, current and frequency through a power converter. It achieves precise control of power output by rectifying, filtering and frequency conversion of the input power signal.
2. Working principle of single-phase variable frequency power supply
A single-phase variable frequency power supply first converts AC power into DC power, and then the electronic components switch the DC power to become AC power. Generally, a high-power inverter uses a thyristor and provides a frequency conversion device. The frequency can be adjusted within a specific range to control the number of revolutions of the motor. The rotation speed can be adjusted within a specific range. The inverter is widely used in the speed regulation of AC motors.
Frequency conversion speed regulation technology is an important development direction of modern power transmission technology. With the development of power electronics technology, AC frequency conversion technology has gradually matured from theory to practice.
Generally divided into rectifier circuit, control circuit, smoothing circuit, inverter circuit, etc.
1. Rectifier circuit
The function of the rectifier circuit is to convert AC power into DC power. The rectifier circuit is usually a single rectifier module.
2. Smoothing circuit
The smoothing circuit contains a pulsating voltage that is six times the frequency of the rectifier power supply, and has a rectified DC voltage, and the DC voltage also fluctuates due to the pulsating current generated by the inverter. Inductors and capacitors are used to absorb pulsating voltage (current) to suppress voltage fluctuations. Since there is a margin in the main circuit of the DC part of the general inverter power supply, the inductor can be omitted and a simple capacitor filter smoothing circuit can be used.
3. Control circuit
Today, variable frequency speed regulators basically use 16-bit, 32-bit microcontrollers or DSPs as the control core to achieve full digital control.
The inverter is a speed regulator that can adjust the output voltage and frequency. The circuit that provides the control signal is called the main control circuit. The control circuit consists of a frequency and voltage "arithmetic circuit", a main circuit "voltage and current detection circuit", and a motor "speed detection circuit". The control signal of the arithmetic circuit is sent to the "drive circuit" and "protection circuit" of the inverter and motor, and the inverter adopts control methods such as speed control, rotation control, and PID.
4. Inverter circuit
The inverter circuit is opposite to the rectifier circuit. It converts the DC voltage into an AC voltage of the required frequency and turns on/off the power switch devices of the upper and lower bridges at a fixed time. Therefore, at the output terminals U, V, and W, a three-phase AC voltage with a phase difference of 120° in electrical angle can be obtained.
The main circuit of the single-phase variable frequency power supply adopts an AC-DC-AC voltage-type frequency conversion circuit centered on rectification, filtering, and inverter. The rectifier part uses a single-phase bridge rectifier module to realize AC/DC conversion, and the filtering link uses a filter capacitor to stabilize the DC voltage.
3.Advantages of single-phase variable frequency power supply
The main circuit of the single-phase variable frequency power supply adopts an AC-DC-AC voltage-type frequency conversion circuit, which is mainly composed of rectification, filtering, and inversion. The rectifier part adopts a single-phase bridge rectifier module to realize AC/DC conversion; the filter link adopts a filter capacitor to stabilize the DC voltage; the inverter part adopts an intelligent power module DIP-IPM to realize DC/AC conversion.
The control circuit of the variable frequency power supply is used to adjust the frequency and amplitude of the output signal of the power supply system to realize voltage and frequency conversion. In order to ensure the safety and reliability of the system, overvoltage and undervoltage detection protection circuits, optocoupler isolation drive circuits, auxiliary power conversion circuits, etc. are set.
1. No radiation interference, low harmonic content, no special treatment, no interference, no noise pollution.
2. Pure and stable sine wave output.
3. Large capacity, small size, light weight (17kg), high efficiency, quiet device, high reliability.
4. Provide standard voltage, frequency and simulation tests for various equipment around the world.
5. Strong overload capacity, instantaneous current can withstand three times the rated current.
6. With overcurrent, over-temperature, short circuit, instantaneous power failure protection and alarm devices.
7. Suitable for resistors, capacitors, inductors and other nonlinear loads.
Single-phase variable frequency power supply can be widely used in power supply equipment in various industries, such as communications, industrial control, medical treatment, rail transportation and other fields. It has the advantages of stable output, high precision, fast response speed, high power factor, etc., and can perform PID control on the output voltage through software program to achieve more flexible and efficient power management.
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